One of the most magical and underrated natural wonders of the West is about to unfold across California beaches.
For four-day periods every year from March to August, legions of small, silver fish called grunion ride the waves ashore for mating rituals, beginning on the nights of the full and new moons.
But this isn’t just any fish spawning.
First, the females bury themselves halfway in the sand with only their heads sticking out and lay their eggs. Then, the males wriggle up and twist and wrap around them. It’s a rare and mysterious orgy unfolding in the dead of night. And it’s all out in the open for public viewing.
For some SoCal families, watching the grunion run is an annual summer tradition. There have been several runs already this year, with sightings reported from La Jolla to Ventura. Another is expected to start tonight.
When the grunions will be running:
This week’s run is predicted go from Tuesday to Friday.
The fish come up on the sand for about two hours at night, as the high tide starts to ebb, usually between 10pm and 2am. The second hour is when the spawning picks up.
The second and third night of the four-night runs tend to be best to see grunion, according to CDFW. The first night, tonight, is the least predictable.
The agency publishes a schedule of what days and times to expect the ritual, based on moon cycles and the timing at San Pedro’s Cabrillo Beach, a known grunion hotspot.
But it all varies.
“The further south that you go, the grunion tend to show up a little bit earlier, and if you go further to the north, they tend to show up a little bit later,” said CDFW environmental scientist Malcolm Tunnell. “We don’t fully understand this. They are a cryptic species.”
Where to see them:
Grunion are a native species and only live off the coast of southern California and northern Mexico. Their usual range is from Santa Barbara to Baja California, although it has been shifting north as climate change heats the oceans.
While you can expect to see grunion in SoCal, the exact beaches where they decide to spawn is something of a mystery, depending on the tides, the sands, and the conditions encountered by the scout fish grunion send out before they decide where to mate.
“We usually say, if it’s a beach where there’s surfing, they like the same surfing waves that people like,” said Karen Martin, a professor of biology at Pepperdine University and leading grunion expert. “But really, any beach that has a nice, wide area where they can come ashore is a potential beach.”
Martin runs a group where citizen scientists can report observations. She said this year the runs have not been as abundant as in the past, but “there have been some nice ones, even earlier this month.”
The CDFW recommends checking social media and calling local lifeguards to ask if grunions have been spotted. Bait and tackle shops may also be able to point you in the right direction.
What are the rules for catching grunion:
Grunion face threats from development on the coast, sea level rise, changes in storm dynamics, and hunting, said Martin.
Since the 1920s, populations have shown signs of decline on-and-off. To protect grunion during their peak spawning period, CDFW prohibits fishing from April through June.
CDFW monitors numbers of the fish, and opens a catch season accordingly each year. In 2022, the season was closed from April through June.
The season is open now with a limit of 30 per person; you can only catch them by hand and anyone over 16 needs to have a fishing license.
Flashlights should be used sparingly, so as not to disrupt them.
“The ideal thing would be to just watch, but if you feel compelled to catch, maybe consider catch and release,” said Martin.
A fish that lives in such a limited geography, she said, needs our care.
“It’s a really remarkable fish.”